Connection method in addition to a functional part which can be used therefor, and flame-retardant total system produced thereby

ABSTRACT

The invention relates to a connection method in addition to a functional part which can be used therefor and to a flame-retardant total system produced in accordance therewith. The invention relates to a method for connecting a single- or multilayer functional part ( 10 ) to a third component ( 20 ), wherein the functional part ( 10 ) has functional elements ( 14, 16 ) projecting on at least one side. Said method is characterized in that the functional part ( 10 ) is formed at least partially from a material which is at least partially transparent to laser light, and in that a blocking layer ( 18 ) is disposed so as to be at least partially opaque to laser light in such a way that after passage of the laser light through the functional part ( 10 ) the laser light inside the blocking layer ( 18 ) generates heat by absorption which is suitable for melting the functional part ( 10 ) and/or the third component ( 20 ) in order to connect them to one another in this way.

The invention relates to a method for connecting a single or multi-layer functional part to a third component, wherein the functional part has functional elements protruding on at least one side. The invention further relates to a functional part, in particular provided for use in such a bond method and a flame-retardant total system, in particular using the joining method and in particular by using said functional part.

From EP-B-0 883 354 a flame retardant functional part, in particular a closure part is known, which is adapted for releasable engagement to a second closure part, comprising:

-   -   a tape-like substrate element made of a flame retardant         polymeric material having an exposed bonding surface and a         support surface;     -   a multiplicity of flexible, resilient stem portions as         functional elements, extending generally perpendicular to said         bonding surface, the distal stem portions having an enlarged         head portion located on a distal end of said stem portion, said         enlarged head portions having a top surface opposite said distal         stem portions and a bonding surface opposite said bonding         surface, the head portions being disposed to permit movement         along different portions of the substrate layer and the         releasable engagement with the second fastener; and     -   a non-flame retardant, pressure sensitive glue applied to said         support surface.

The known fastener can satisfy the requirements of the vertical flammability test F.A.R. 25.853(a)(1)(i) without being attached to a substrate. Such provision or specification relates to such fastening systems, in particular relating to applications in vehicle and aircraft technology and are used, for example, for fastening wall panels to the support structure of a cabin of a rail vehicle or attaching upholstery materials and cushion materials to aircraft passenger seats and the like. Today, in particular in the field of aircraft engineering, increased demands are placed on the flammability of such fastening systems, which can be significantly higher than the data in the above specification.

In the known solution described above, in a preferred embodiment, furthermore the non-flame-retardant adhesive is a foam layer of a pressure-sensitive acrylic foam adhesive, such composed glues are described by way of example in the WO-A-2005/017060 in more detail.

Even though both the pressure-sensitive glue and the aforementioned acrylic foam glue have in practice proved of value in attaching functional parts, such Kletten® or Velcro® fasteners and in particular tape-like Gecko® adhesive systems based on Van der Waals forces, to third components, it cannot be completely ruled out that the adhesive bond yields or fails and as a result the functional part is unintentionally detached from the third component, for example in the form of floor or wall parts of an aircraft or vehicle cabin or a part of an aircraft seat or vehicle passenger seat. In particular, in public places or in case of accessible components, such as seats of any kind, in particular in the area of moving aircraft and vehicles, operators, installers and users may be at risk, if in particular larger elements, such as floor and wall coverings, connected by the functional part to the third component, detach unintentionally through failure of the adhesive bond. In addition, production costs for the above-mentioned conventional glues increase rapidly, i.e. there is a need to search for improved bond systems.

Starting from this basis, the invention addresses the problem of providing, with respect to the prior art, improved solutions allowing, in a more cost-effective and functionally reliable manner, for an improved bond between the said parts in addition to or alternatively to the known adhesive bonding systems.

This object is achieved by a method having the features of claim 1 in its entirety and a functional part according to the configuration of features of claim 6 and a flame retardant total system according to the configuration of features of claim 9.

Based on the fact that according to the characterizing part of claim 1, the functional part is at least partially formed from an at least partially laser-permeable material, and that an at least partially laser-impermeable barrier layer is arranged such that after the laser light has penetrated the functional part, the laser light within the barrier layer generates heat by absorption which is suitable for partial melting the functional and/or third component to connect them to each other in this way, the bond between the functional part and third component is achieved in a particularly rational manner by means of laser radiographic welding. In particular, by forming the laser-impermeable barrier layer between the third component and the allocated side of the functional part to be attached, the energy absorption in the immediate welding area of the two parts to each other is ensured, and the material area heated and fused by the laser light, which is to be located both on the functional part and on the third component, forms the joining element for fusing the adjacent joining partners to each other and establishes a secure bond, which will reliably hold up even under strain or stress, such as heat input, vibration, impact or shock-like stress etc.

In a particularly preferred embodiment of the connecting process according to the invention, the functional part is provided with a barrier layer on the side facing away from the laser light entrance side and/or the barrier layer is formed by the third component itself or by parts of this component and/or by a separate component.

In the simplest case, the functional part is formed by a preferably transparent, in particular laser-permeable adhesion closure part or adhesion part and the functional part has a suitable laser light-absorbing barrier layer on the underside facing away from the functional element. Insofar as the aforementioned functional parts are produced by a so-called chill-cast molding process (DE 10 2004 012 067 A1), the mentioned barrier can be intrinsically integrated in the substrate tape side, on which the functional elements, such as mushroom-shaped closure heads, locking hooks, adhesion elements, loop material etc. protrude, during molding, for example by connecting nano-particulate fluids that may also contain appropriate amounts of graphite to the other plastic material of the tape-like substrate element.

A further possibility consists in applying an additional barrier film, for instance in the form of a black-body film, to the backing of the substrate tape facing away from the functional elements, which can also be achieved by a blade coating or coating process, resulting in a firm bond between the black film and the functional part. The latter configuration is particularly useful if a functional part designed as an adhesion closure part comprises a base fabric of warp and weft threads, into which the fastener elements are additionally woven as functional elements via pile threads in the above manner. Such functional elements may be formed by interlocking elements that are formed at regular intervals from single protruding stem parts, which open at their respective free end in a widened head part and/or formed of closing loops.

In a particularly preferred method, it is provided that the functional part has a multi-layer design and a substrate element having the closing or adhesion parts as functional elements is formed as the one layer of the functional part, which is laterally at least partially overlapped by another layer of the functional part having a specifiable excess that is at least partially formed by a laser-permeable material, and, after having passed through it, the laser light strikes the barrier layer or is guided to it. In such a case, the laser bond can only be made by the additional layer of the functional part and the one layer of the functional part having the substrate element and the closing or adhesion parts can also be impermeable to laser light, i.e. pigmented closure and adhesion parts may be used. Provided the substrate element has stem and head parts as functional elements, it is also possible to guide the light in the direction of the barrier layer via the respective head and stem parts, i.e. the laser light can be guided through the stem parts in the manner of light in a fiber optic cable.

It is particularly preferred in a process according to the invention that in addition to the laser bond, a second bond system is introduced between the functional part and the third component as an additional safeguard against unintentional disengagement. In this way, the cured adhesive bond may possibly fail due to severe mechanical stress; but the bond between the functional part and the third component is still secured by the laser bond and the joining areas fused to each other. If, however, very high temperatures occur, the laser bond may yield, especially if the area of the joint partners formed of plastic materials should melt away, with the result that the bond will still be secured by the adhesive input. The, in this way redundant, system that covers multiple stresses, therefore meets the strictest requirements of aeronautical engineering and complies with the latest requirements specifications in that respect.

It is surprising to an average person skilled in the art that combining two completely different bond systems (lasing and bonding) yields such improved results; there is no equivalent in the prior art.

Below, the solution according to the invention is explained in detail with reference to various exemplary embodiments in the drawing. In the schematic figures, which are not to scale,

FIG. 1 shows a side view of a section of a produced in accordance with a micro-replication process adhesion part having a blackbody film underneath;

FIG. 2 is a representation corresponding to FIG. 1 of an adhesion closure part preferably produced in accordance with a chill-cast process having stem and head parts protruding on a substrate tape as interlocking elements with intrinsically embedded nano-particulate black bodies;

FIG. 3 shows the fabric image of an adhesion closure part as a further third embodiment in plan view;

FIG. 4 shows a side view of the planar adhesion closure part according to FIG. 3 having a blackbody film underneath;

FIG. 5 shows a perspective plan view of a multilayer functional part in arched form as part of a flame-resistant total system.

FIG. 1 shows a section of a functional part 10 having a substrate element 12 in the form of a substrate tape of predetermined length, transverse and height dimensions. Vertically protruding stem parts 14 are arranged on the substrate element 12, which widen towards their upper free end and each form head parts 16, which are integrally connected to the allocatable stem parts 14. The relevant stem parts 14, along with the head parts 16, form from the individual functional elements of the functional part 10.

Such functional part 10 can be produced by a so-called micro-replication process as shown in DE 10 2004 012 067 A1, by way of an example. The functional part shown in FIG. 1 forms an adhesive part, wherein the generated functional element structure is very small, i.e. there may be more than 16,000 functional elements per cm2 on the tape-like substrate 12. In particular, the functional elements in the plane of projection extend not only in the longitudinal direction of the tape, but also in accordance with predetermined patterns (not shown), transverse to the direction of the tape. The adhesion of the free sides of the head parts 16 on structures to be attached, such as glass parts, plastic sheets, but also preferably coated fabrics etc. is based on so-called van der Waals forces, which can reach very high adhesion forces due to the plurality of functional elements. To release the structures to be attached from the adhesion part in the form of the functional part 10 in accordance with FIG. 1, it is best to peel off their respective surface preferably from the surface of the head parts 16 at an angle of 90° or more to release the adhesion via the van der Waals forces. The attachment and release processes described above can be conducted several times, depending on the configuration of the closing system, preferably thousands of times.

To be able to produce the functional part 10 according to the illustration of FIG. 1 using the micro-replication process mentioned above, special inorganic and organic elastomers are used for the functional part 10. Polyvinyl siloxanes and silicone elastomers cross-linked by adhesion in the form of 2-component systems and acrylates have proven to be particularly advantageous input materials. The plastic materials described above can be designed such that they are, at least partially, transparent, in particular, laser-permeable, with the advantage that laser light can penetrate the functional part 10 shown in FIG. 1 from top to bottom more or less freely.

As can also be derived from FIG. 1, there is a barrier layer 18 on the underside of the tape-like substrate element 12, which is largely laser-impermeable and is formed in particular in the manner of a black body. Thus, the barrier layer 18 can, in accordance with FIG. 1, consist of a so-called blackbody film. Preferably, the film 18 can be blade-coated to the underside of the carrier belt 12 such that the tape 12 and film 18 enter into a fixed bond with each other. However, it is also possible to glue the film 18 to the underside of the tape 12 by means of suitable glue. Such two-layer functional part 10 can then be placed on a third component 20, which preferably likewise consists of plastic materials, although this is not mandatory. In particular, the third component 20 can be formed by a frame element of a vehicle or aircraft passenger seat or part of wall parts of a vehicle or aircraft cabin. If the laser light now passes through the functional part 10, it encounters the barrier layer 18, generating heat by absorption within the barrier layer 18, which is suitable for surface-melting the functional part 10 and/or third component 20, to firmly join them to each other.

The wavelength of the laser radiation is adapted to the individual absorption characteristics of the thermoplastic material of the blackbody film 18, wherein the absorption coefficient for the selected wavelength is preferably between 5% and 40%. Preferably, laser radiation having a wavelength in a wavelength range from 400 nm to 2000 nm is preferably used for the embodiments described herein above. Preferably, the laser radiation or the individual laser beams as a whole have a Gaussian beam profile. By a suitable choice of the laser radiation, their division and focus in the system areas of the partial components to be connected described above can be firmly connected or welded in a cost effective and functionally reliable manner.

For special bond applications, the use of a pulsed laser has proven to be advantageous. With proper selection of the laser and the materials used, a connecting melting region having a diameter or width of less than 1 mm, preferably less than 0.5 mm, furthermore preferably less than 0.1 mm can be produced, which is important because, in view of the small size of the components to be interconnected, larger interconnecting areas could be damaging to the material and would result in the attachment system becoming unusable. Suitable lasers for transmission techniques using laser light, are for example, solid-state lasers such as Nd:YAG lasers having a wavelength of 1064 nm and high-performance diode lasers having wavelengths in the range from 800 to 1000 nm. The mentioned black-body film 18 can be a polyamide film having embedded sensitive particles, in particular color pigments, such as carbon black or the like, these particles having a corresponding minimum temperature stability. Film thicknesses of 0.03 to 0.1 mm, preferably 0.05 mm, can be used.

The aforementioned mentioned barrier layer 18 can also form an independent component, which shall then be inserted between the functional component 10 and the third component 20. After the components have been held together, which can be done by hand, the bond process using laser light takes place. Obviously, the barrier layer 18 may also be arranged on the third component 20 or third component 20 itself consists on its outer peripheral side of a suitable barrier layer material, for example in the form of sprayed soot, to ensure the absorbency at the third component 20 during lasing and therefore the secure bond of the functional part 10 to the third component 20.

Hereinafter, further embodiments shall be explained only to the extent by which they differ significantly from the preceding embodiment.

The embodiment of FIG. 2 is a so-called adhesion closure part, as can be produced for example by a process as indicated by DE 10 2007 015 441 A1. Other shaping processes can also be used, for example using shaping rollers, the pertinent manufacturing process is referred to as “chill-cast” shaping process in technical terminology. In accordance with the exemplary embodiment of FIG. 1, the functional part 10 is in turn formed by a tape-like substrate element 12 having protruding stem parts 14 and end-side head parts 16 integrally arranged thereon. In contrast to the solution according to FIG. 1, however, the adhesion closure part according to FIG. 2 has been designed larger by several orders of magnitude and is intended in particular to interact with another adhesion closure part (not shown) to create such a repeatedly releasable and closeable adhesion closure. For instance, a loop material of another adhesion closure part (not shown) can hook into the protruding projections under the mushroom-shaped head parts 16 to permit such bond. Further bond solutions are known in which comparably formed head parts of another adhesion closure part (not shown) enter into a releasable closure, i.e. bond with the shown functional part 10 of FIG. 2. Such adhesion closure parts and adhesion closure systems are well known, i.e. at this point they will not be elaborated on. Such adhesion closure parts are particularly suitable to attach upholstery materials, also of a textile nature, onto upholstery parts.

So-called additives shall constitute the barrier layer 18 of the present exemplary embodiment of FIG. 2, for example in the form of so-called carbon nanotubes (CNTs) and/or carbon fibers, which can be integrated in the base material of the plastic during molding. Such carbon materials also have the advantage of electrical conductivity, i.e. any static loads of the functional part 10 can be discharged via the carbon materials. The aforementioned additives, in particular in the form of carbon nanotubes, are also available in liquid form, i.e. such liquid can be placed on the exposed underside of the substrate tape 12 during molding.

Another option of manufacturing would also consist in first filling the mold cavities of the mold with laser-permeable material in a first molding step and then rapidly dyeing the plastic material towards the unattached bottom of the substrate tape 12 to form the absorption layer as a barrier layer 18.

The additional third embodiment in accordance to FIGS. 3 and 4 shows in FIG. 3 a partial plan view of a sheet-like adhesion closure part, which can be arbitrarily extended within the image plane of the blank part in one and in the other image direction and the geometrical dimensions of planar materials as a functional part 10 depend on the requirements of the weaving device, in which the closure part is manufactured. In particular for the later use of such closure parts, they may be designed in the form of roll-like reeled adhesion closure tapes (not shown). The closure part as a functional part 10 consists of warp threads 22 and weft threads 24 woven together in cross arrangement forming the base fabric 26 for the adhesion closure part. Furthermore, the base fabric 26 is equipped with functional threads 28 as functional elements of the functional part 10, forming a further part of the base fabric 26. The individual functional thread 28 then forms the tape-like adhesion closure part of the individual functional or closure elements, as explained in greater detail below. Furthermore, in technical terminology the threads used are often called yarns.

Looking in the perspective of FIG. 3, the production direction for the closure part to be produced is depicted on its top face by an arrow 30. In the illustrated arrangement of FIG. 3, the weft threads 24 are formed arc-shaped in the manner of a sinusoidal or cosinusoidal wave and, at the intersection of warp threads 22 and weft threads 24, the warp threads 22 run in parallel to the production direction 30 and parallel to each other in a rectilinear arrangement. In the illustrated embodiment, only the weft threads 24 are arranged arcuate in the base fabric 26, such that, in an alternating sequence, the respective weft threads 24 run over a warp thread 22 and run under the one immediately next to it. The advantage of such an arcuate configuration is explained in more detail in DE 10240986 B by the holder of the proprietary rights, such that it shall not be explained in greater detail in this context.

At the point where the respective weft threads run under the warp threads in the base fabric 26, the functional or pile thread 28 forms an overlying loop 32, which is immediately adjacent to another loop 32, resulting in a kind of V-link. There are here, however, other types of links conceivable, such as the inclusion of the functional thread 28 in a W-shaped manner or the like, for example.

Said loops 32 form a type of fastener elements from the functional elements and if the loops 32, as shown in FIG. 2, remain closed, a frieze adhesion closure part is obtained, wherein the hook or mushroom-like closure elements (see FIG. 2) can engage in the relevant loops 32 to obtain a releasable fastener as a whole as part of a closure or attachment system. There is also, according to the illustration of FIG. 4, which depicts a kind of longitudinal view of the longitudinal alignment of arrow 30 on the functional part 10, the option of melting, at least partially, the individual loops 32 along a dividing line 34, in this way after the free ends of the open loop have surface-melted, both a closure element with stem part 14 and mushroom-shaped head part 16 are formed corresponding to the illustration according to FIG. 2.

As the base fabric shown in FIG. 3 has largely rectangular recesses between the individual thread systems 22, 24 and 28, there is the option of the laser light penetrating such distances for the purpose of hitting a barrier layer 18 arranged on the underside of the functional part 10 as a further layer, which in turn, can be designed for example in the manner of a blackbody film. In this manner woven, knitted and interlaced closure materials can be attached to third body components by means of a laser.

When using the thread solution according to FIGS. 3 and 4, a separate barrier layer, for instance in the form of a blackbody film 18 to be attached, can be omitted, by just rendering individual threads of the base fabric 26, consisting of warp and weft threads 22, 24, black, for instance by using carbon, resulting in a material having a high absorbency for laser light.

In the embodiment of FIG. 5 an adhesion closure part is again used as functional part 10, having a tape-shaped substrate element 12, from which the individual stem parts 14 and their end-side head portions 16 protrude with a specifiable projection. Such adhesion closure part as a functional part 10 can in turn be obtained by a production process, as indicated in the embodiment according to FIG. 2. However, both the stem part 14 and the head part 16 are shaped like polygons in the present case, in particular in the form of a hexagon. The functional part 10 according to the embodiment of FIG. 5 may be laser permeable but does not need to be. Preferably, however, the functional part 10 is multi-layered according to the representation of FIG. 5 and has, on its underside, as part of the functional part 10, a further layer 36, which laterally protrudes, as viewed in longitudinal direction, along both longitudinal edges 38 of the first layer, with a specifiable excess of the first functional part 35 with its protruding functional elements 14, 16. At least in the region of the excess, the additional layer 36 is formed to be laser-permeable; but the entire additional layer 36 can also be formed laser permeable.

On the bottom of the first functional layer 35 and second functional layer 36, there is a third functional layer 42, which is formed by a glue, in particular in the form of a polyurethane hot melt glue. Such polyurethane hot melt glue preferably has the following formula:

-   -   10-90% polyester-polyol,     -   0 to 50% polyester-polyol,     -   5 to 35% polyisocyanate,     -   2 to 50% flame retardants such as phosphorus and/or triazine         compounds free of antimony and halogens, and     -   if required, additives such as catalysts and stabilizers.

In this way, a solvent-free hot melt glue, cross-linked by moisture, is realized on the basis of reactive polyurethane tripolymers. The relevant melting glue as an additional third functional layer 42 is instantly reactive and can be directly connected to a third component 20 in a glue-fixed bond manner by placing it thereon. If the third component 20 is formed as a black body in the area of the projection 40 of the additional second layer 36, the overall composite shown in FIG. 5 can be securely attached via the laser-permeable projection 40 using laser light. Due to this laser bond and the glue bond, a redundant overall system has been created; if one bond system fails, the other bond system ensures a secure bond.

If no redundant system is desired, the glue layer 42 can be omitted and the bond to third component 20 can be established via a correspondingly provided barrier layer 18 for laser light using the laser-permeable projection 40 of the second functional layer 36. As a matter of course, viewed in direction of FIG. 5, the glue layer 42 can be covered downwards by a backing paper (not shown), after the removal of which, the glue layer is then exposed and adheres to the third component 20.

The solution according to the invention, in which the respective third component 20 is an injection-molded part, and is made, for example, from a polyphenylene sulfide (PPS), can be implemented particularly well. For the additional second layer 36 depicted in FIG. 5, flame-retardant plastics are used, for instance compounds of polycarbonate (PC) with acrylonitrile butadiene styrene (ABS). Overall, a flame retardant total fastening system is created using the aforementioned materials, pointing in particular towards a use in aircraft technology and passenger transport. Instead of the active agent formulation for the glue as a third functional layer 42, alternatively a flame retardant acrylic glue can also be used. 

1. A method for connecting a single- or multi-layer functional part (10) to a third component (20), wherein the functional part (10) has functional elements (14, 16) protruding on at least one side. Said method is characterized in that the functional part (10) is formed at least partially from a material which is at least partially transparent to laser light, and in that a barrier layer (18) is disposed so as to be at least partially opaque to laser light in such a way that after passage of the laser light through the functional part (10) the laser light inside the barrier layer (18) generates heat by absorption, which is suitable for melting the functional part (10) and/or the third component (20) in order to connect them to each other in this way.
 2. The method according to claim 1, characterized in that the functional part (10) at the side facing away from the laser light entrance side is provided with the barrier layer (18) and/or that the barrier layer (18) is formed by the third component (20) itself or parts of this component (20) and/or is formed by an independent component.
 3. The method according to claim 1, characterized in that a substrate element (12) with the closing or adhesion parts as functional elements is formed as the one layer (35) of the functional part (10), in which another layer (36) of the functional part (10) having a specifiable excess, extends laterally, at least partially, extends over it, which is at least partially formed by a laser-permeable material, and, after having passed through it, the laser light strikes the barrier layer (18) or is guided to it.
 4. The method according to claim 1, characterized in that, in addition to the laser bond, a second bond system (42) is introduced between the functional part (10) and the third component (20) as an additional safeguard against unintentional disengagement.
 5. The method according to claim 1, characterized in that the attachment of an adhesive compound (42) is used as the second bond system.
 6. A functional part, in particular intended for use in a connecting method according to claim 1, wherein, on at least one side of a substrate element (12), the above functional elements are present, characterized in that the functional part (10) is at least partially formed by a laser-impermeable material and that the functional part (10), on its side facing away from the laser light, has a barrier layer (18) at least partially impermeable to laser-light.
 7. The functional part according to claim 6, characterized in that the barrier layer (18) is an integral part of the substrate element (12) and/or is intrinsically incorporated into it and/or is arranged as a separate layer on the side facing away from the functional elements of the substrate element (12).
 8. The functional part according to claim 6, characterized in that it is formed in multiple layers, the one layer (35) is formed by the substrate element (12) having the function elements and the additional further layer (36) at least partially laterally protrudes beyond the first layer (35), and that the additional layer (36) is at least partially formed by a laser-permeable material, at least in the area of the projection.
 9. A flame retardant total system, in particular using a bond method according to claim 1, characterized in that a further layer (36) extends laterally, at least partially, over a substrate element (12) of a functional part (10) having protruding functional elements as a layer (35), which is at least partially laser-permeable, such that at the points of extension, the bond to a third member (20) is at least partially established by means of laser light absorption, and that as an additional safeguard between the functional part (10) and the third component (20), a adhesive bond (42) is provided.
 10. The total system according to claim 9, characterized in that the adhesive bond (42) is provided at the locations between the functional part (10) and the third component (20), which are excluded from the laser light bond.
 11. The total system according to claim 9 or 10, characterized in that the third component (20) is part of an aircraft passenger seat to be provided with a cover and/or upholstery material and that the functional part (10) is formed at least partially of an adhesion closure part, which forms with a correspondingly shaped adhesion closure part on the cover and/or upholstery material a repeatedly releasable adhesion closure part. 